/**
 * @file
 * IGMP - Internet Group Management Protocol
 *
 */

/*
 * Copyright (c) 2002 CITEL Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of CITEL Technologies Ltd nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CITEL TECHNOLOGIES AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL CITEL TECHNOLOGIES OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is a contribution to the lwIP TCP/IP stack.
 * The Swedish Institute of Computer Science and Adam Dunkels
 * are specifically granted permission to redistribute this
 * source code.
 */

/*-------------------------------------------------------------
   Note 1)
   Although the rfc requires V1 AND V2 capability
   we will only support v2 since now V1 is very old (August 1989)
   V1 can be added if required

   a debug print and statistic have been implemented to
   show this up.
   -------------------------------------------------------------
   -------------------------------------------------------------
   Note 2)
   A query for a specific group address (as opposed to ALLHOSTS)
   has now been implemented as I am unsure if it is required

   a debug print and statistic have been implemented to
   show this up.
   -------------------------------------------------------------
   -------------------------------------------------------------
   Note 3)
   The router alert rfc 2113 is implemented in outgoing packets
   but not checked rigorously incoming
   -------------------------------------------------------------
   Steve Reynolds
   ------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
* RFC 988  - Host extensions for IP multicasting                         - V0
* RFC 1054 - Host extensions for IP multicasting                         -
* RFC 1112 - Host extensions for IP multicasting                         - V1
* RFC 2236 - Internet Group Management Protocol, Version 2               - V2  <- this code is based on this RFC (it's the "de facto" standard)
* RFC 3376 - Internet Group Management Protocol, Version 3               - V3
* RFC 4604 - Using Internet Group Management Protocol Version 3...       - V3+
* RFC 2113 - IP Router Alert Option                                      -
*----------------------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
* Includes
*----------------------------------------------------------------------------*/

#include "lwip/opt.h"

#if LWIP_IGMP /* don't build if not configured for use in lwipopts.h */

#include "lwip/igmp.h"
#include "lwip/debug.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/ip.h"
#include "lwip/inet.h"
#include "lwip/inet_chksum.h"
#include "lwip/netif.h"
#include "lwip/icmp.h"
#include "lwip/udp.h"
#include "lwip/tcp.h"
#include "lwip/stats.h"

#include "string.h"

/*-----------------------------------------------------------------------------
* Globales
*----------------------------------------------------------------------------*/

static struct igmp_group* igmp_group_list;
static struct ip_addr allsystems;
static struct ip_addr allrouters;

/**
 * Initialize the IGMP module
 */
void
igmp_init(void)
{
    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_init: initializing\n"));

    IP4_ADDR(&allsystems, 224, 0, 0, 1);
    IP4_ADDR(&allrouters, 224, 0, 0, 2);
}

#ifdef LWIP_DEBUG
/**
 * Dump global IGMP groups list
 */
void
igmp_dump_group_list()
{
    struct igmp_group *group = igmp_group_list;

    while (group != NULL)
    {
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_dump_group_list: [%"U 32_F "] ", (u32_t)(group->group_state)));
        ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
        LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->interface));
        group = group->next;
    }
    LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
}
#else
#define igmp_dump_group_list()
#endif /* LWIP_DEBUG */

/**
 * Start IGMP processing on interface
 *
 * @param netif network interface on which start IGMP processing
 */
err_t
igmp_start(struct netif *netif)
{
    struct igmp_group* group;

    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: starting IGMP processing on if %p\n", netif));

    group = igmp_lookup_group(netif, &allsystems);

    if (group != NULL)
    {
        group->group_state = IGMP_GROUP_IDLE_MEMBER;
        group->use++;

        /* Allow the igmp messages at the MAC level */
        if (netif->igmp_mac_filter != NULL)
        {
            LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: igmp_mac_filter(ADD "));
            ip_addr_debug_print(IGMP_DEBUG, &allsystems);
            LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
            netif->igmp_mac_filter( netif, &allsystems, IGMP_ADD_MAC_FILTER);
        }

        return ERR_OK;
    }

    return ERR_MEM;
}

/**
 * Stop IGMP processing on interface
 *
 * @param netif network interface on which stop IGMP processing
 */
err_t
igmp_stop(struct netif *netif)
{
    struct igmp_group *group = igmp_group_list;
    struct igmp_group *prev  = NULL;
    struct igmp_group *next;

    /* look for groups joined on this interface further down the list */
    while (group != NULL)
    {
        next = group->next;
        /* is it a group joined on this interface? */
        if (group->interface == netif)
        {
            /* is it the first group of the list? */
            if (group == igmp_group_list)
            {
                igmp_group_list = next;
            }
            /* is there a "previous" group defined? */
            if (prev != NULL)
            {
                prev->next = next;
            }
            /* disable the group at the MAC level */
            if (netif->igmp_mac_filter != NULL)
            {
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
                ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
                LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
                netif->igmp_mac_filter(netif, &(group->group_address), IGMP_DEL_MAC_FILTER);
            }
            /* free group */
            memp_free(MEMP_IGMP_GROUP, group);
        }
        else
        {
            /* change the "previous" */
            prev = group;
        }
        /* move to "next" */
        group = next;
    }
    return ERR_OK;
}

/**
 * Report IGMP memberships for this interface
 *
 * @param netif network interface on which report IGMP memberships
 */
void
igmp_report_groups( struct netif *netif)
{
    struct igmp_group *group = igmp_group_list;

    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_report_groups: sending IGMP reports on if %p\n", netif));

    while (group != NULL)
    {
        if (group->interface == netif)
        {
            igmp_delaying_member( group, IGMP_JOIN_DELAYING_MEMBER_TMR);
        }
        group = group->next;
    }
}

/**
 * Search for a group in the global igmp_group_list
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search for
 * @return a struct igmp_group* if the group has been found,
 *         NULL if the group wasn't found.
 */
struct igmp_group *
igmp_lookfor_group(struct netif *ifp, struct ip_addr *addr)
{
    struct igmp_group *group = igmp_group_list;

    while (group != NULL)
    {
        if ((group->interface == ifp) && (ip_addr_cmp(&(group->group_address), addr)))
        {
            return group;
        }
        group = group->next;
    }

    /* to be clearer, we return NULL here instead of
     * 'group' (which is also NULL at this point).
     */
    return NULL;
}

/**
 * Search for a specific igmp group and create a new one if not found-
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search
 * @return a struct igmp_group*,
 *         NULL on memory error.
 */
struct igmp_group *
igmp_lookup_group(struct netif *ifp, struct ip_addr *addr)
{
    struct igmp_group *group = igmp_group_list;

    /* Search if the group already exists */
    group = igmp_lookfor_group(ifp, addr);
    if (group != NULL)
    {
        /* Group already exists. */
        return group;
    }

    /* Group doesn't exist yet, create a new one */
    group = memp_malloc(MEMP_IGMP_GROUP);
    if (group != NULL)
    {
        group->interface          = ifp;
        ip_addr_set(&(group->group_address), addr);
        group->timer              = 0; /* Not running */
        group->group_state        = IGMP_GROUP_NON_MEMBER;
        group->last_reporter_flag = 0;
        group->use                = 0;
        group->next               = igmp_group_list;

        igmp_group_list = group;
    }

    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_lookup_group: %sallocated a new group with address ", (group ? "" : "impossible to ")));
    ip_addr_debug_print(IGMP_DEBUG, addr);
    LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", ifp));

    return group;
}

/**
 * Remove a group in the global igmp_group_list
 *
 * @param group the group to remove from the global igmp_group_list
 * @return ERR_OK if group was removed from the list, an err_t otherwise
 */
err_t
igmp_remove_group(struct igmp_group *group)
{
    err_t err = ERR_OK;

    /* Is it the first group? */
    if (igmp_group_list == group)
    {
        igmp_group_list = group->next;
    }
    else
    {
        /* look for group further down the list */
        struct igmp_group *tmpGroup;
        for (tmpGroup = igmp_group_list; tmpGroup != NULL; tmpGroup = tmpGroup->next)
        {
            if (tmpGroup->next == group)
            {
                tmpGroup->next = group->next;
                break;
            }
        }
        /* Group not found in the global igmp_group_list */
        if (tmpGroup == NULL)
        {
            err = ERR_ARG;
        }
    }
    /* free group */
    memp_free(MEMP_IGMP_GROUP, group);

    return err;
}

/**
 * Called from ip_input() if a new IGMP packet is received.
 *
 * @param p received igmp packet, p->payload pointing to the ip header
 * @param inp network interface on which the packet was received
 * @param dest destination ip address of the igmp packet
 */
void
igmp_input(struct pbuf *p, struct netif *inp, struct ip_addr *dest)
{
    struct ip_hdr *    iphdr;
    struct igmp_msg*   igmp;
    struct igmp_group* group;
    struct igmp_group* groupref;

    /* Note that the length CAN be greater than 8 but only 8 are used - All are included in the checksum */
    iphdr = p->payload;
    if (pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4)) || (p->len < IGMP_MINLEN))
    {
        pbuf_free(p);
        IGMP_STATS_INC(igmp.lenerr);
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: length error\n"));
        return;
    }

    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: message from "));
    ip_addr_debug_print(IGMP_DEBUG, &(iphdr->src));
    LWIP_DEBUGF(IGMP_DEBUG, (" to address "));
    ip_addr_debug_print(IGMP_DEBUG, &(iphdr->dest));
    LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", inp));

    /* Now calculate and check the checksum */
    igmp = (struct igmp_msg*)p->payload;
    if (inet_chksum(igmp, p->len))
    {
        pbuf_free(p);
        IGMP_STATS_INC(igmp.chkerr);
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: checksum error\n"));
        return;
    }

    /* Packet is ok so find an existing group */
    group = igmp_lookfor_group(inp, dest); /* use the incoming IP address! */

    /* If group can be found or create... */
    if (!group)
    {
        pbuf_free(p);
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP frame not for us\n"));
        return;
    }

    /* NOW ACT ON THE INCOMING MESSAGE TYPE... */
    switch (igmp->igmp_msgtype)
    {
    case IGMP_MEMB_QUERY: {
        /* IGMP_MEMB_QUERY to the "all systems" address ? */
        if ((ip_addr_cmp(dest, &allsystems)) && (igmp->igmp_group_address.addr == 0))
        {
            /* THIS IS THE GENERAL QUERY */
            LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: General IGMP_MEMB_QUERY on \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));

            if (igmp->igmp_maxresp == 0)
            {
                IGMP_STATS_INC(igmp.v1_rxed);
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: got an all hosts query with time== 0 - this is V1 and not implemented - treat as v2\n"));
                igmp->igmp_maxresp = IGMP_V1_DELAYING_MEMBER_TMR;
            }

            IGMP_STATS_INC(igmp.group_query_rxed);
            groupref = igmp_group_list;
            while (groupref)
            {
                /* Do not send messages on the all systems group address! */
                if ((groupref->interface == inp) && (!(ip_addr_cmp(&(groupref->group_address), &allsystems))))
                {
                    igmp_delaying_member( groupref, igmp->igmp_maxresp);
                }
                groupref = groupref->next;
            }
        }
        else
        {
            /* IGMP_MEMB_QUERY to a specific group ? */
            if (group->group_address.addr != 0)
            {
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_MEMB_QUERY to a specific group "));
                ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
                if (ip_addr_cmp(dest, &allsystems))
                {
                    LWIP_DEBUGF(IGMP_DEBUG, (" using \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
                    /* we first need to re-lookfor the group since we used dest last time */
                    group = igmp_lookfor_group(inp, &igmp->igmp_group_address);
                }
                else
                {
                    LWIP_DEBUGF(IGMP_DEBUG, (" with the group address as destination [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
                }

                if (group != NULL)
                {
                    IGMP_STATS_INC(igmp.unicast_query);
                    igmp_delaying_member( group, igmp->igmp_maxresp);
                }
            }
        }
        break;
    }
    case IGMP_V2_MEMB_REPORT: {
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_V2_MEMB_REPORT\n"));

        IGMP_STATS_INC(igmp.report_rxed);
        if (group->group_state == IGMP_GROUP_DELAYING_MEMBER)
        {
            /* This is on a specific group we have already looked up */
            group->timer = 0; /* stopped */
            group->group_state = IGMP_GROUP_IDLE_MEMBER;
            group->last_reporter_flag = 0;
        }
        break;
    }
    default: {
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: unexpected msg %d in state %d on group %p on if %p\n",
                                 igmp->igmp_msgtype, group->group_state, &group, group->interface));
        break;
    }
    }

    pbuf_free(p);
    return;
}

/**
 * Join a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should join a new group
 * @param groupaddr the ip address of the group which to join
 * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 */
err_t
igmp_joingroup(struct ip_addr *ifaddr, struct ip_addr *groupaddr)
{
    err_t err = ERR_VAL;            /* no matching interface */
    struct igmp_group *group;
    struct netif      *netif;

    /* make sure it is multicast address */
    LWIP_ERROR("igmp_joingroup: attempt to join non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL; );
    LWIP_ERROR("igmp_joingroup: attempt to join allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL; );

    /* loop through netif's */
    netif = netif_list;
    while (netif != NULL)
    {
        /* Should we join this interface ? */
        if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr))))
        {
            /* find group or create a new one if not found */
            group = igmp_lookup_group(netif, groupaddr);

            if (group != NULL)
            {
                /* This should create a new group, check the state to make sure */
                if (group->group_state != IGMP_GROUP_NON_MEMBER)
                {
                    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
                }
                else
                {
                    /* OK - it was new group */
                    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to new group: "));
                    ip_addr_debug_print(IGMP_DEBUG, groupaddr);
                    LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

                    /* If first use of the group, allow the group at the MAC level */
                    if ((group->use == 0) && (netif->igmp_mac_filter != NULL))
                    {
                        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: igmp_mac_filter(ADD "));
                        ip_addr_debug_print(IGMP_DEBUG, groupaddr);
                        LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
                        netif->igmp_mac_filter(netif, groupaddr, IGMP_ADD_MAC_FILTER);
                    }

                    IGMP_STATS_INC(igmp.join_sent);
                    igmp_send(group, IGMP_V2_MEMB_REPORT);

                    igmp_start_timer(group, IGMP_JOIN_DELAYING_MEMBER_TMR);

                    /* Need to work out where this timer comes from */
                    group->group_state = IGMP_GROUP_DELAYING_MEMBER;
                }
                /* Increment group use */
                group->use++;
                /* Join on this interface */
                err = ERR_OK;
            }
            else
            {
                /* Return an error even if some network interfaces are joined */
                /** @todo undo any other netif already joined */
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: Not enought memory to join to group\n"));
                return ERR_MEM;
            }
        }
        /* proceed to next network interface */
        netif = netif->next;
    }

    return err;
}

/**
 * Leave a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should leave a group
 * @param groupaddr the ip address of the group which to leave
 * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 */
err_t
igmp_leavegroup(struct ip_addr *ifaddr, struct ip_addr *groupaddr)
{
    err_t err = ERR_VAL;            /* no matching interface */
    struct igmp_group *group;
    struct netif      *netif;

    /* make sure it is multicast address */
    LWIP_ERROR("igmp_leavegroup: attempt to leave non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL; );
    LWIP_ERROR("igmp_leavegroup: attempt to leave allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL; );

    /* loop through netif's */
    netif = netif_list;
    while (netif != NULL)
    {
        /* Should we leave this interface ? */
        if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr))))
        {
            /* find group */
            group = igmp_lookfor_group(netif, groupaddr);

            if (group != NULL)
            {
                /* Only send a leave if the flag is set according to the state diagram */
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: Leaving group: "));
                ip_addr_debug_print(IGMP_DEBUG, groupaddr);
                LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

                /* If there is no other use of the group */
                if (group->use <= 1)
                {
                    /* If we are the last reporter for this group */
                    if (group->last_reporter_flag)
                    {
                        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: sending leaving group\n"));
                        IGMP_STATS_INC(igmp.leave_sent);
                        igmp_send(group, IGMP_LEAVE_GROUP);
                    }

                    /* Disable the group at the MAC level */
                    if (netif->igmp_mac_filter != NULL)
                    {
                        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: igmp_mac_filter(DEL "));
                        ip_addr_debug_print(IGMP_DEBUG, groupaddr);
                        LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
                        netif->igmp_mac_filter(netif, groupaddr, IGMP_DEL_MAC_FILTER);
                    }

                    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: remove group: "));
                    ip_addr_debug_print(IGMP_DEBUG, groupaddr);
                    LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

                    /* Free the group */
                    igmp_remove_group(group);
                }
                else
                {
                    /* Decrement group use */
                    group->use--;
                }
                /* Leave on this interface */
                err = ERR_OK;
            }
            else
            {
                /* It's not a fatal error on "leavegroup" */
                LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: not member of group\n"));
            }
        }
        /* proceed to next network interface */
        netif = netif->next;
    }

    return err;
}

/**
 * The igmp timer function (both for NO_SYS=1 and =0)
 * Should be called every IGMP_TMR_INTERVAL milliseconds (100 ms is default).
 */
void
igmp_tmr(void)
{
    struct igmp_group *group = igmp_group_list;

    while (group != NULL)
    {
        if (group->timer != 0)
        {
            group->timer -= 1;
            if (group->timer == 0)
            {
                igmp_timeout(group);
            }
        }
        group = group->next;
    }
}

/**
 * Called if a timeout for one group is reached.
 * Sends a report for this group.
 *
 * @param group an igmp_group for which a timeout is reached
 */
void
igmp_timeout(struct igmp_group *group)
{
    /* If the state is IGMP_GROUP_DELAYING_MEMBER then we send a report for this group */
    if (group->group_state == IGMP_GROUP_DELAYING_MEMBER)
    {
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_timeout: report membership for group with address "));
        ip_addr_debug_print(IGMP_DEBUG, &(group->group_address));
        LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->interface));

        igmp_send(group, IGMP_V2_MEMB_REPORT);
    }
}

/**
 * Start a timer for an igmp group
 *
 * @param group the igmp_group for which to start a timer
 * @param max_time the time in multiples of IGMP_TMR_INTERVAL (decrease with
 *        every call to igmp_tmr())
 */
void
igmp_start_timer(struct igmp_group *group, u8_t max_time)
{
    /**
     * @todo Important !! this should be random 0 -> max_time. Find out how to do this
     */
    group->timer = max_time;
}

/**
 * Stop a timer for an igmp_group
 *
 * @param group the igmp_group for which to stop the timer
 */
void
igmp_stop_timer(struct igmp_group *group)
{
    group->timer = 0;
}

/**
 * Delaying membership report for a group if necessary
 *
 * @param group the igmp_group for which "delaying" membership report
 * @param maxresp query delay
 */
void
igmp_delaying_member( struct igmp_group *group, u8_t maxresp)
{
    if ((group->group_state == IGMP_GROUP_IDLE_MEMBER) ||
        ((group->group_state == IGMP_GROUP_DELAYING_MEMBER) && (maxresp > group->timer)))
    {
        igmp_start_timer(group, (maxresp) / 2);
        group->group_state = IGMP_GROUP_DELAYING_MEMBER;
    }
}


/**
 * Sends an IP packet on a network interface. This function constructs the IP header
 * and calculates the IP header checksum. If the source IP address is NULL,
 * the IP address of the outgoing network interface is filled in as source address.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
            protocol header; if dest == IP_HDRINCL, p already includes an IP
            header and p->payload points to that IP header)
 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 *         IP  address of the netif used to send is used as source address)
 * @param dest the destination IP address to send the packet to
 * @param ttl the TTL value to be set in the IP header
 * @param proto the PROTOCOL to be set in the IP header
 * @param netif the netif on which to send this packet
 * @return ERR_OK if the packet was sent OK
 *         ERR_BUF if p doesn't have enough space for IP/LINK headers
 *         returns errors returned by netif->output
 */
err_t
igmp_ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
                  u8_t ttl, u8_t proto, struct netif *netif)
{
    /* This is the "router alert" option */
    u16_t ra[2];

    ra[0] = htons(ROUTER_ALERT);
    ra[1] = 0x0000; /* Router shall examine packet */
    return ip_output_if_opt(p, src, dest, ttl, 0, proto, netif, ra, ROUTER_ALERTLEN);
}

/**
 * Send an igmp packet to a specific group.
 *
 * @param group the group to which to send the packet
 * @param type the type of igmp packet to send
 */
void
igmp_send(struct igmp_group *group, u8_t type)
{
    struct pbuf*     p    = NULL;
    struct igmp_msg* igmp = NULL;
    struct ip_addr src  = { 0 };
    struct ip_addr*  dest = NULL;

    /* IP header + "router alert" option + IGMP header */
    p = pbuf_alloc(PBUF_TRANSPORT, IGMP_MINLEN, PBUF_RAM);

    if (p)
    {
        igmp = p->payload;
        LWIP_ASSERT("igmp_send: check that first pbuf can hold struct igmp_msg",
                    (p->len >= sizeof(struct igmp_msg)));
        ip_addr_set(&src, &((group->interface)->ip_addr));

        if (type == IGMP_V2_MEMB_REPORT)
        {
            dest = &(group->group_address);
            IGMP_STATS_INC(igmp.report_sent);
            ip_addr_set(&(igmp->igmp_group_address), &(group->group_address));
            group->last_reporter_flag = 1; /* Remember we were the last to report */
        }
        else
        {
            if (type == IGMP_LEAVE_GROUP)
            {
                dest = &allrouters;
                ip_addr_set(&(igmp->igmp_group_address), &(group->group_address));
            }
        }

        if ((type == IGMP_V2_MEMB_REPORT) || (type == IGMP_LEAVE_GROUP))
        {
            igmp->igmp_msgtype  = type;
            igmp->igmp_maxresp  = 0;
            igmp->igmp_checksum = 0;
            igmp->igmp_checksum = inet_chksum( igmp, IGMP_MINLEN);

            igmp_ip_output_if(p, &src, dest, IGMP_TTL, IP_PROTO_IGMP, group->interface);
        }

        pbuf_free(p);
    }
    else
    {
        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_send: not enough memory for igmp_send\n"));
    }
}

#endif /* LWIP_IGMP */
